Understanding the Anomalous J–V Curves in Carbon‐Based Perovskite Solar Cells as a Structural Transition Induced by Ion Diffusion
Résumé
The investigation of hole transport layer‐free mesoporous carbon perovskite solar cells by analyzing current–voltage ( J – V ) curves under different scan rates, light intensities, and temperatures is presented. A distinctive bump in the curves is identified, previously reported in the literature. The voltage at the inflection point of this transition shows a linear correlation with the scan rate, directly yielding a characteristic relaxation time. Increasing temperature demonstrates a reduction in the magnitude and characteristic time of the bump. It also indicates an activation energy of 0.8 eV, suggesting a diffusion mechanism. Importantly, the intensity of the illumination has no influence on the overall behavior, indicating that the phenomenon is not a photovoltaic processes. It is proposed that the bump originates from transition between a metastable state at high scan rates and a stable one reached after relaxation. To accurately replicate the measured J – V curves, a novel lumped circuit model is introduced and validated. A schematic microstructural model depicts the reversible reduction in photocurrent as a decline in charge transfer capacity caused by the diffusion of large ions at the mesoporous titanuim dioxyde interface. Ultimately, this study also suggests a plausible reason for the well‐known hysteresis commonly observed with perovskite solar cells.
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Licence : CC BY - Paternité
Licence : CC BY - Paternité